Afamitresgene autoleucel for advanced synovial sarcoma and myxoid round cell liposarcoma (SPEARHEAD-1): an international, open-label, phase 2 trial

BACKGROUND

Afamitresgene autoleucel (afami-cel) showed acceptable safety and promising efficacy in a phase 1 trial (NCT03132922). The aim of this study was to further evaluate the efficacy of afami-cel for the treatment of patients with HLA-A*02 and MAGE-A4-expressing advanced synovial sarcoma or myxoid round cell liposarcoma.

METHODS

SPEARHEAD-1 was an open-label, non-randomised, phase 2 trial done across 23 sites in Canada, the USA, and Europe. The trial included three cohorts, of which the main investigational cohort (cohort 1) is reported here. Cohort 1 included patients with HLA-A*02, aged 16-75 years, with metastatic or unresectable synovial sarcoma or myxoid round cell liposarcoma (confirmed by cytogenetics) expressing MAGE-A4, and who had received at least one previous line of anthracycline-containing or ifosfamide-containing chemotherapy. Patients received a single intravenous dose of afami-cel (transduced dose range 1·0 × 109-10·0 × 109 T cells) after lymphodepletion. The primary endpoint was overall response rate in cohort 1, assessed by a masked independent review committee using Response Evaluation Criteria in Solid Tumours (version 1.1) in the modified intention-to-treat population (all patients who received afami-cel). Adverse events, including those of special interest (cytokine release syndrome, prolonged cytopenia, and neurotoxicity), were monitored and are reported for the modified intention-to-treat population. This trial is registered at ClinicalTrials.gov, NCT04044768; recruitment is closed and follow-up is ongoing for cohorts 1 and 2, and recruitment is open for cohort 3.

FINDINGS

Between Dec 17, 2019, and July 27, 2021, 52 patients with cytogenetically confirmed synovial sarcoma (n=44) and myxoid round cell liposarcoma (n=8) were enrolled and received afami-cel in cohort 1. Patients were heavily pre-treated (median three [IQR two to four] previous lines of systemic therapy). Median follow-up time was 32·6 months (IQR 29·4-36·1). Overall response rate was 37% (19 of 52; 95% CI 24-51) overall, 39% (17 of 44; 24-55) for patients with synovial sarcoma, and 25% (two of eight; 3-65) for patients with myxoid round cell liposarcoma. Cytokine release syndrome occurred in 37 (71%) of 52 of patients (one grade 3 event). Cytopenias were the most common grade 3 or worse adverse events (lymphopenia in 50 [96%], neutropenia 44 [85%], leukopenia 42 [81%] of 52 patients). No treatment-related deaths occurred.

INTERPRETATION

Afami-cel treatment resulted in durable responses in heavily pre-treated patients with HLA-A*02 and MAGE-A4-expressing synovial sarcoma. This study shows that T-cell receptor therapy can be used to effectively target solid tumours and provides rationale to expand this approach to other solid malignancies.

FUNDING

Adaptimmune.

Abstract 892: Afamitresgene autoleucel (afami-cel; formerly ADP-A2M4) demonstrates durable clinical responses by inducing broad immune engagement with anti-tumor activity

Afami-cel is a mixed CD4+ CD8+ autologous T-cell therapy engineered to target the cancer testis antigen melanoma-associated antigen A4 in HLA-A*02-positive patients with advanced/metastatic synovial sarcoma or myxoid/round cell liposarcoma (MRCLS). Pooled data from the Phase 1 (NCT03132922) and Phase 2 (SPEARHEAD-1, NCT04044768) trials of afami-cel showed an acceptable benefit to risk profile with an overall response rate of 36.2% and a median duration of response of 52.0 weeks.1 To support the continued investigation of potential mechanisms of durable anti-tumor activity, we previously showed that afami-cel induces broad and enduring peripheral cytokine responses2 and that afami-cel tumoral infiltration is associated with increased presence of activated and proliferative cytotoxic T-cells in the tumor microenvironment.3 Here, we report the results of translational analyses exploring the cooperation between afami-cel-induced innate and adaptive immune responses pooled from the Phase 1 and 2 trials. Methods included measurement of 92 biomarkers related to apoptosis, chemotaxis, metabolism, tumor immunity promotion/suppression, and vascular/tissue remodeling in pre- and post-infusion serum samples from 38 patients. We also conducted multiplex immunofluorescence and gene set variation analysis of Reactome immune system pathway categories and microenvironment cell populations in RNA sequencing data from pre- and post-infusion biopsies from ≥15 patients. Serum analyses showed that patients with a clinical benefit as defined by RECIST v1.1 had significantly greater post-infusion levels of chemotactic markers (Kruskal-Wallis; p<0.05 for partial response [PR] compared to progressive disease, p<0.01 for PR compared to stable disease), indicating higher signaling related to immune-cell recruitment towards lesions. Tumor analyses showed increased expression of genes associated with innate and adaptive immunity, and cytokine signaling, in post-infusion biopsies, including T-cell receptor signaling-related expression, which was consistent with relatively greater spatial protein detection of pro-immune infiltrate. This profile was associated with longer progression-free survival. In conclusion, our data suggest that afami-cel induces peripheral and tumoral innate and adaptive immune responses, a hallmark of durable anti-tumor activity. Updated patient sample data will be presented. 1. D'Angelo SP, et al. J Clin Oncol. 2022;40:16_suppl:11562. 2. D’Angelo SP, et al. Poster 146 presented at: CTOS 2021; Virtual. 3. Van Tine, BA et al. Paper 61 presented at: CTOS 2022; Vancouver, BC, Canada.

Citation Format: Cheryl McAlpine, Martin Isabelle, Robyn Broad, Revashnee Naidoo, Ashley Liddle, Elizabeth Duperret, Paul Noto, Ruoxi Wang, Dzmitry Batrakou, Sumit Middha, Chris Evans. Afamitresgene autoleucel (afami-cel; formerly ADP-A2M4) demonstrates durable clinical responses by inducing broad immune engagement with anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 892.

Autologous T cell therapy for MAGE-A4+ solid cancers in HLA-A*02+ patients: a phase 1 trial

Affinity-optimized T cell receptors can enhance the potency of adoptive T cell therapy. Afamitresgene autoleucel (afami-cel) is a human leukocyte antigen-restricted autologous T cell therapy targeting melanoma-associated antigen A4 (MAGE-A4), a cancer/testis antigen expressed at varying levels in multiple solid tumors. We conducted a multicenter, dose-escalation, phase 1 trial in patients with relapsed/refractory metastatic solid tumors expressing MAGE-A4, including synovial sarcoma (SS), ovarian cancer and head and neck cancer ( NCT03132922 ). The primary endpoint was safety, and the secondary efficacy endpoints included overall response rate (ORR) and duration of response. All patients (N = 38, nine tumor types) experienced Grade ≥3 hematologic toxicities; 55% of patients (90% Grade ≤2) experienced cytokine release syndrome. ORR (all partial response) was 24% (9/38), 7/16 (44%) for SS and 2/22 (9%) for all other cancers. Median duration of response was 25.6 weeks (95% confidence interval (CI): 12.286, not reached) and 28.1 weeks (95% CI: 12.286, not reached) overall and for SS, respectively. Exploratory analyses showed that afami-cel infiltrates tumors, has an interferon-γ-driven mechanism of action and triggers adaptive immune responses. In addition, afami-cel has an acceptable benefit-risk profile, with early and durable responses, especially in patients with metastatic SS. Although the small trial size limits conclusions that can be drawn, the results warrant further testing in larger studies.

Abstract LB001: Identifying MAGE-A4-positive tumors for SPEAR T-cell therapies in HLA-A*02-eligible patients

Autologous T-cells engineered with T-cell receptors (TCRs) targeting tumor antigens are promising therapies for metastatic solid cancers.1 Specific peptide enhanced affinity receptor (SPEAR) T-cell therapies are T-cells with engineered HLA-restricted TCRs that precisely target tumor cells with specific antigens, such as MAGE-A4 (a cancer testis antigen), presented on the surface by HLA molecules. In SPEAR T-cell clinical trials targeting MAGE-A4, a 2-step prescreen is done before enrolment. 1) Patients undergo HLA typing via a high-resolution (allelic, 4-digit) sequence-based assay, and those who are positive for the inclusion alleles (HLA-A*02:01P, 02:02P, 02:03P, 02:06P) and not positive for the exclusion allele A*02:05P are eligible. 2) Tumor MAGE-A4 testing is done via an immunohistochemical clinical trial assay (MAGE-A4+ cutoff: ≥30% tumor cell staining at ≥2+ intensity) in HLA-eligible patients. A screening protocol (NCT02636855) has been used in Phase 1 trials of first- and next-generation SPEAR T-cells targeting MAGE-A4 (NCT03132922, NCT04044859) with responses in multiple MAGE-A4+ tumors. As of November 19, 2021, 6,168 patients with 9 solid tumor types were screened at 32 sites across North America and Europe in this screening protocol; among which, 2,744 were HLA-eligible (eligibility rate: 45%, range per tumor type: 42%-55%). HLA-A*02:01 was the most frequent HLA-A*02 allele. Of these HLA-eligible patients, 1,549 had tumor tissues evaluable for MAGE-A4 expression; among which, 313 were MAGE-A4+ (MAGE-A4+ rate: 20%, range: 8%-54%) (Table). MAGE-A4 showed highest prevalence in synovial sarcoma and myxoid/round cell liposarcoma but was seen across all tumor types investigated. Our results will be discussed in the context of tumor histopathology, disease status, and demography. HLA and MAGE-A4 biomarker data will inform the therapeutic opportunities for SPEAR T-cells targeting MAGE-A4 in metastatic solid cancers. 1. D’Angelo et al. Cancer Discov. 2018;8:944.

HLA eligibility and MAGE-A4 prevalence in a screening protocol (NCT02636855) Indication Esophageal cancer Esophagogastric junction cancer Gastric cancer Head and neck squamous cell carcinoma Non-small cell lung cancer Melanoma Ovarian cancer Urothelial cancer Synovial sarcoma and myxoid/round cell liposarcoma HLA screened (N) 284 228 271 601 3189 668 539 270 118 HLA eligible (%) 46 45 43 42 43 50 49 43 55 MAGE-A4 evaluable (N) 104 91 73 200 457 245 225 93 61 MAGE-A4 positive (%) 22 25 8 22 14 16 24 32 54

Citation Format: Tianjiao Wang, Jean-Marc Navenot, Stavros Rafail, Mark Carroll, Ruoxi Wang, Cheryl McAlpine, Swethajit Biswas, Francine Brophy, Erica Elefant, Paige Bayer, Sandra McGuigan, Dennis Williams, George Blumenschein, Marcus Butler, Jeffrey M. Clarke, Justin F. Gainor, Ramaswamy Govindan, Victor Moreno, Janet Tu, David S. Hong. Identifying MAGE-A4-positive tumors for SPEAR T-cell therapies in HLA-A*02-eligible patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB001.

Phase I Study of Safety, Tolerability, and Efficacy of Tebentafusp Using a Step-Up Dosing Regimen and Expansion in Patients With Metastatic Uveal Melanoma

PURPOSE

This phase I study aimed to define the recommended phase II dose (RP2D) of tebentafusp, a first-in-class T-cell receptor/anti-CD3 bispecific protein, using a three-week step-up dosing regimen, and to assess its safety, pharmacokinetics, pharmacodynamics, and preliminary clinical activity in patients with metastatic uveal melanoma (mUM).

METHODS

In this open-label, international, phase I/II study, HLA-A*02 or HLA-A*02:01+ patients with mUM received tebentafusp 20 μg once in week 1 and 30 μg once in week 2. Dose escalation (starting at 54 μg) began at week 3 in a standard 3 + 3 design to define RP2D. Expansion-phase patients were treated at the RP2D (20-30-68 μg). Blood and tumor samples were collected for pharmacokinetics/pharmacodynamics assessment, and treatment efficacy was evaluated for all patients with baseline efficacy data as of December 2017.

RESULTS

Between March 2016 and December 2017, 42 eligible patients who failed a median of two previous treatments were enrolled: 19 in the dose escalation cohort and 23 in an initial dose expansion cohort. Of the dose levels investigated, 68 μg was identified as the RP2D. Most frequent treatment-emergent adverse events regardless of attribution were pyrexia (91%), rash (83%), pruritus (83%), nausea (74%), fatigue (71%), and chills (69%). Toxicity attenuated following the first three doses. The overall response rate was 11.9% (95% CI, 4.0 to 25.6). With a median follow-up of 32.4 months, median overall survival was 25.5 months (range, 0.89-31.1 months) and 1-year overall survival rate was 67%. Treatment was associated with increased tumor T-cell infiltration and transient increases in serum inflammatory mediators.

CONCLUSION

Using a step-up dosing regimen of tebentafusp allowed a 36% increase in the RP2D compared with weekly fixed dosing, with a manageable side-effect profile and a signal of efficacy in mUM.

373 Enhancement of TCR-engineered T-cells targeting MAGE-A4 antigen by co-expression of CD8α and inhibition of AKT signaling during ex vivo T-cell expansion

Background

Autologous Specific Peptide Enhanced Affinity Receptor (SPEAR) T-cells targeting MAGE-A4 can be effective treatment for solid tumors.1–3 To improve efficacy, we developed a next-generation SPEAR-T cell targeting MAGE-A4 co-expressing CD8α (ADP-A2M4CD8). ADP-A2M4CD8 is under investigation in the Phase 1 SURPASS trial (NCT04044859). Enhancements have also been made to the manufacturing process with an AKT inhibitor (AKTi) during ex vivo expansion to provide a greater proliferative potential and enhanced memory phenotype.4

Methods

SPEAR-T cells were manufactured using a Lentiviral vector with CD8α and MAGE-A4 targeted TCR genes. AKTi was added during ex vivo expansion. T-cell attributes were evaluated, including markers of differentiation (flow cytometry), capacity for in vitro tumor lysis (Incucyte) and changes to gene expression (scRNASeq) initially assessed with the first-gen product. Post-infusion, the presence of transduced T-cells in the peripheral circulation (PCR) and levels of inflammatory cytokines in serum (MesoScale Discovery Assay [MSD]) were evaluated.

Results

As of May 24, 2021, 18 patients with 9 different primary tumor types were evaluable. Twelve pts received product that had AKTi during manufacture. Five patients had objective responses (RECIST), and 10 had stable disease. Responses occurred at lower MAGE-A4 expression levels and lower transduced T-cell doses relative to the first-gen product targeting MAGE-A4.1 CD4 T-cells from manufactured ADP-A2M4CD8 demonstrated direct in vitro tumor cell killing similar to CD8+ T-cells (Incucyte). scRNASeq gene expression profiles of first-gen ADP-A2M4 product manufactured with AKTi revealed the AKTi-expanded T-cells had a greater proliferation or an enhanced memory phenotype; scRNASeq analyses are ongoing for the ADP-A2M4CD8 product.An increase in IL-12 levels (MSD) in serum post-infusion suggests that endogenous immune cells are being activated, further resulting in increased levels of IFN gamma (MSD) secretion relative to patients who received first-gen product. Manufacturing with AKTi resulted in T-cells with a less differentiated phenotype (flow cytometry), and post-infusion was associated with enhanced antigen-specific serum cytokine responses, increased proliferative state (i.e., elevated levels of IL-2), and higher persistence of T-cells in peripheral blood by PCR.

Conclusions

SPEAR T-cells targeting MAGE-A4 expressing cancers have been enhanced by co-expressing CD8α and adding AKTi during manufacture. These enhanced products improve CD4+ T-cell killing, release more inflammatory cytokines, proliferate more robustly with an early memory phenotype, and better engage the patient‘s endogenous immune system when compared to first-gen products or next-gen manufactured without AKTi.

Trial Registration

NCT04044859

References

Hong, et al. ASCO 2020.

D’Angelo, et al. ASCO 2021.

Hong, et al. SITC 2020.

Mardilovich, et al. SITC 2020.

376 Radiation sub-study to characterize safety and tolerability of low-dose radiation in combination with afami-cel in patients with advanced cancers (NCT03132922)

Background

Autologous cell therapies with an engineered T-cell receptor targeting MAGE-A4 have shown responses in patients with synovial sarcoma1 with additional responses in myxoid/round cell liposarcoma (MRCLS), head and neck, lung, esophagogastric junction, and melanoma cancers.2 3 Low-dose radiation may control tumor growth locally and modulate stroma of solid tumors,4 potentially facilitating T-cell infiltration into tumors and antitumor activity.

Methods

Sub-study designed to assess safety, tolerability, and efficacy in up to 10 patients with low-dose radiation in combination with lymphodepleting chemotherapy, followed by afami-cel (an autologous TCR cell T-cell therapy targeting MAGE-A4). Eligible patients are HLA-A*02^+ with MAGE-A4 expressing tumors including urothelial, melanoma, head and neck, ovarian, non-small cell lung, esophageal, gastric, synovial sarcoma, and MRCLS cancers. Patients receive afami-cel by infusion following low-dose radiation and lymphodepleting chemotherapy. Radiation was 4.2–7 Gy per lesion or isocenter (maximum of 5). Lymphodepleting regimen was IV fludarabine 30 mg/m^2/day for 4 days (−7 to −4) and cyclophosphamide 600 mg/m^2/day for 3 days (−7 to −5). Afami-cel doses ranged from 1.2 x 10^9 to 10 x 10^9 transduced cells. Pts receive afami-cel infusion on Day 1.

Results

As of Dec 27, 2020, a total of 8 patients, including 4 patients (1 male) with melanoma (2), HNSCC (1), or ovarian (1) cancers received low-dose radiation and afami-cel. Most frequently reported AEs (4/4 pts) were leukopenia/decreased white blood cell count, lymphopenia/decreased lymphocyte count, and neutropenia/decreased neutrophil count; all of which were related to the lymphodepletion regimen. The most commonly (>1 patient) reported AEs considered related to T-cell infusion were cytokine release syndrome (2/4 pts) and fatigue (2/4 pts). Two patients had a total of 5 SAEs: adrenal insufficiency, hyperglycemia, neurotoxicity, pneumonia aspiration, and pneumothorax. The only SAE considered to be related to treatment was Grade 3 neurotoxicity. Best overall responses per RECIST 1.1: 1 partial response (melanoma, −42% in target lesions), 2 stable diseases (ovarian cancer, −23%; HNSCC, no change), and 1 patient did not have post-baseline scans yet. Translational analyses showed peripheral persistence and serum cytokine response profiles consistent with that of afami-cel monotherapy, whilst a relatively greater T cell infiltration in tumor biopsies was evident.

Conclusions

Afami-cel with low-dose radiation has had an acceptable safety profile. Most AEs were consistent with those typically experienced by cancer patients undergoing lymphodepletion cytotoxic chemotherapy and cellular therapy. Infused T-cells were observed in tumor biopsies at high frequency, and one patient exhibited a clinical partial response.

Trial Registration

NCT03132922

References

Van Tine BA, et al. CTOS 2020.

Hong DS, et al. ASCO 2020.

Hong DS, et al. SITC 2020.

De Selm C, et al. Mol Ther 2018;26(11):2542–2552.

36 Feasibility of Resistance Exercise to Failure at Different Loads in Frail and Healthy Older Adults?

Introduction

Resistance training (RT) is the most effective way to increase muscle mass and function in older adults both with/without sarcopenia/frailty. In younger adults, when RT is performed to muscle failure the load lifted does not mediate the magnitude of response, but there are no studies in older adults. We aimed to determine the feasibility of recruitment to a RT intervention working to muscle failure at different loads in frail and healthy older adults.

Methods

We performed an 8-week randomised feasibility trial of lower limb RT to volitional muscular failure, at high and low load. Participants were recruited via hospital outpatient clinics and newspaper advertisements. Outcomes included: frailty assessment (Fried criteria); muscle strength (maximum voluntary contraction/one-repetition maximum); functional abilities (Short Physical Performance Battery); safety/adverse events were recorded via a log, and patient experiences from focus groups.

Results

110 people were assessed for eligibility, and 58 randomised (frail n = 6, prefrail n = 20, robust n = 32) to either high (n = 30) or low load (n = 28) groups. Mean age of participants was 72 years (range 65–93), 36 were female, 22 male. Session attendance was 95% (high load) and 90.4% (low load). Most participants were recruited via advertisements. All participants reported feeling safe and reassured in the RT sessions. Two participants had a serious adverse event, one related to RT (hypotension) and several had adverse events (three intervention-related). Pain was reported at both loads (high n = 9, low n = 8) yet all completed. There were no differences (P > 0.05) in effects of RT outcome variables between low and high load groups.

Conclusion

In this feasibility trial the recruitment of frail patients via clinics was limited. Performing supervised RT to muscle failure in older adults was safe/acceptable and the load at which RT was performed did not influence its efficacy. Future research into the effectiveness of such RT is warranted.

Tebentafusp, A TCR/Anti-CD3 Bispecific Fusion Protein Targeting gp100, Potently Activated Antitumor Immune Responses in Patients with Metastatic Melanoma

PURPOSE

Tebentafusp is a first-in-class bispecific fusion protein designed to target gp100 (a melanoma-associated antigen) through a high affinity T-cell receptor (TCR) binding domain and an anti-CD3 T-cell engaging domain, which redirects T cells to kill gp100-expressing tumor cells. Here, we report a multicenter phase I/II trial of tebentafusp in metastatic melanoma (NCT01211262) focusing on the mechanism of action of tebentafusp.

PATIENTS AND METHODS

Eighty-four patients with advanced melanoma received tebentafusp. Treatment efficacy, treatment-related adverse events, and biomarker assessments were performed for blood-derived and tumor biopsy samples obtained at baseline and on-treatment.

RESULTS

Tebentafusp was generally well-tolerated and active in both patients with metastatic uveal melanoma and patients with metastatic cutaneous melanoma. A 1-year overall survival rate of 65% was achieved for both patient cohorts. On-treatment cytokine measurements were consistent with the induction of IFNγ pathway-related markers in the periphery and tumor. Notably, tebentafusp induced an increase in serum CXCL10 (a T-cell attractant) and a reduction in circulating CXCR3+ CD8+ T cells together with an increase in cytotoxic T cells in the tumor microenvironment. Furthermore, increased serum CXCL10 or the appearance of rash (likely due to cytotoxic T cells targeting gp100-expressing skin melanocytes) showed a positive association with patient survival.

CONCLUSIONS

These data suggest that redirecting T cells using a gp100-targeting TCR/anti-CD3 bispecific fusion protein may provide benefit to patients with metastatic melanoma. Furthermore, the activity observed in these two molecularly disparate melanoma classes hints at the broad therapeutic potential of tebentafusp.

Abstract 4554: Functionally distinct T cell subsets contribute to ImmTAC-mediated anti-tumor response

Introduction: Bispecific T cell engagers hold promise for effective cancer treatment. The anti-tumor activity of these therapeutics molecules predominantly relies on their capacity to induce direct killing of tumor cells by engaging the cytotoxic machinery of polyclonal CD8+ T cells. However, the impact of additional functionally different T cell populations that can be engaged alongside CD8+ T cells remains unclear. ImmTAC molecules are a novel class of bispecific fusion proteins that use an affinity-enhanced monoclonal TCR to target tumor antigen-derived peptides presented by HLA, and an anti-CD3 monomeric antibody to engage T cells. Tebentafusp, our lead clinical candidate, targets a gp100-derived peptide and is under clinical investigation in metastatic melanoma. Preliminary data revealed T cell activation, trafficking and infiltration into the tumor bed in patients responding to treatment. Importantly not only CD8+ T cells, but also different subsets of CD4+ T cells appeared to be activated, mobilized and redirected to the tumor site following tebentafusp treatment, suggesting a potential contribution of these T cell subsets to the anti-tumor response. The aim of this study was to investigate in vitro the functional capacity of different T cell populations, besides CD8+ T cells, following ImmTAC-mediated redirection toward cancer cells.

Methods: Th1, Th2, Th17 CD4+ T cells, γδ T cells and Mucosal-Associated Invariant T cells (MAIT) were isolated from healthy volunteers and their functional response following exposure to ImmTAC in the presence of target cells was analysed.

Results: In addition to CD8+ T cells, other T cell populations, were activated in vitro by ImmTAC and elicited a range of effector functions that may differentially contribute to anti-tumor responses. For example, we found that γδ T cells were able to mount rapid and potent cytokine and cytotoxic responses against cancer cells upon redirection with ImmTAC. The mechanisms that underpin our in vitro observations and the potential correlations in patients treated with tebentafusp are under investigation. Conclusions: Multiple T cells populations display functionally distinct responses following ImmTAC-mediated redirection. These results will add valuable insight to our understanding of bispecific T cell engager mechanism of action. In addition, they will help guide rationale for improving the design of these therapeutic molecules and select appropriate combination strategies.

Citation Format: Adel Benlahrech, David K. Cole, Christopher J. Holland, Rupert Kenefeck, Rahul C. Khanolkar, Cheryl McAlpine, Sion Lewis, Angela Valerio-Fernandes, Mariantonella Vardeu, David Berman, Marco Lepore. Functionally distinct T cell subsets contribute to ImmTAC-mediated anti-tumor response [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4554.

Pharmacodynamic effect of IMCgp100 (TCR–CD3 bispecific) on peripheral cytokines and association with overall survival in patients with advanced melanoma

9523

Background: ImmTAC molecules are unique TCR–anti-CD3 bispecifics that redirect T cells against intracellular antigens. IMCgp100, an ImmTAC targeting melanocyte-expressed gp100 antigen, has demonstrated monotherapy activity in advanced melanoma and can cause rash and cytokine-mediated AEs, hypothesized to be on-target (gp100) or effector (CD3) mediated. A preclinical MoA for T cell bispecifics suggests chemokine CXCL10 redirection of CXCR3+ T cells from blood into antigen-positive tissues; this has not been clinically validated. Methods: 84 HLA-A2+ pts with advanced melanoma (n = 61 cutaneous [CM], n = 19 uveal [UM], n = 4 other) received IMCgp100 (NCT01211262). Serum (n = 40) and PBMC (n = 22) samples were taken pre- and post-infusion to analyze changes in cytokines and circulating T cells. Pre- (n = 16) and post-treatment (n = 11) tumor biopsies were analyzed by IHC for CD3, PD-L1 and gp100 expression; tumor RNA (n = 12) was analyzed for gene expression. Results: IMCgp100 induced a transient increase in IFNg-inducible cytokines, most prominently CXCL10. A greater increase in serum CXCL10 was associated with longer OS (p = 0.0002), tumor shrinkage (p = 0.003), and greater transient reduction in peripheral CXCR3+CD8+ T cells (p = 0.001). Reduction in CXCR3+ CD8+ T cells also trended with longer OS (p = 0.02), and tumor shrinkage (p = 0.03). 3/16 pre-treatment biopsies had < 1% gp100 expression (all progressive disease). 8/11 biopsies post-IMCgp100 had increased CD3+ T cells compared with matched pre-treatment samples (associated with baseline gp100 but not PD-L1 expression). Based on tumor biopsy gene expression analysis, IMCgp100 increased T cell markers, IFNg-inducible and cytotoxicity-related genes. Conclusions: The association of clinical benefit with increased serum CXCL10 and decreased peripheral CXCR3+ T cells supports the MoA of IMCgp100-induced T cell redirection and activation. Tumor biopsy results support IMCgp100 redirection of T cells to antigen-positive tumor. A Phase II trial in CM (NCT02535078), a Phase I/II trial in UM (NCT02570308), and a Pivotal RCT in UM (NCT03070392) are ongoing. Clinical trial information: NCT01211262.

Abstract 3655: Biomarker strategy to guide the clinical development of ImmTACTM molecules, a novel class of bispecific T cell engaging biologic drugs

IMCgp100, a first in class immunotherapy, is a T cell redirecting bispecific biologic comprising an affinity enhanced T-cell receptor specific for gp100 and an anti-CD3 scFV. Phase I/IIa data has provided evidence of a favourable safety profile, and durable responses in both cutaneous and uveal melanoma have been observed. To complement the clinical studies we have developed a comprehensive biomarker strategy to aid our understanding of pharmacodynamics, patient response and potential mechanisms of resistance which includes analysis of markers in both the tumour and periphery. The data obtained to date provide evidence of the pharmacodynamic effects of the molecule including chemokine/cytokine release, in both the tumor and periphery, and lymphocyte infiltration into tumors. In addition, changes in the levels of certain chemokines following the first dose of IMCgp100 were associated with tumor shrinkage. The biomarker strategy we have developed forms the basis for the support of the on-going Ph II development of IMCgp100 in both cutaneous and uveal melanoma and for other ImmTAC molecules, as single agents and in combination, for the treatment of solid tumours.

Citation Format: Cheryl McAlpine, David Krige, Sandra Herrero-Gonzalez, Sarah Franklin, Jacob Hurst, William Shingler, Sanjay Patel, Andy Johnson, Debbie Parker, Christina M. Coughlin, Namir J. Hassan, Bent K. Jakobsen. Biomarker strategy to guide the clinical development of ImmTACTM molecules, a novel class of bispecific T cell engaging biologic drugs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3655. doi:10.1158/1538-7445.AM2017-3655

Intra-patient escalation dosing strategy with IMCgp100 results in mitigation of T-cell based toxicity and preliminary efficacy in advanced uveal melanoma

9531

Background: IMCgp100 is a bispecific biologic capable of redirecting T cells against the melanocyte-associated antigen gp100. In the first-in-human (FIH) clinical trial, preliminary efficacy of IMCgp100 in advanced uveal melanoma (UM) was observed; however, cases of severe T cell-mediated toxicities with the first 2 doses limited dosing to 50 mcg QW. This phase 1 study was designed to implement intra-patient escalation to mitigate toxicity and maximize exposure of IMCgp100. Methods: Using a 3+3 design, HLA-A2+ pts with metastatic UM were treated with low weekly (QW) dosing of IMCgp100 iv at Cycle 1, Day 1 (C1D1) (20 mcg) and C1D8 (30 mcg), followed by the escalated cohort dose administered at C1D15 and beyond. Results: Nineteen metastatic UM pts with a median of 3 prior lines of therapy (range 0 - 8) were treated across 4 target dose cohorts (60, 70, 80, and 75 mcg). Fifteen of 19 pts remain on treatment at the data cutoff (25Nov16). Enrollment completed 15Sep16. DLT was observed in 1 of 6 pts in the 70-mcg cohort (LFT elevation), and 2 of 4 pts treated at 80 mcg QW (LFT and bilirubin elevation). The 80 mcg dose level was not tolerated and a 75 mcg cohort was enrolled. Six pts were treated at 75 mcg without DLT; this dose was identified as the MTD and RP2D. All 3 DLT resolved without corticosteroids and all pts resumed IMCgp100. Frequent related AE included pruritus (84%), pyrexia (84%), fatigue (74%), hypotension (74%) and peripheral edema (63%). Gr 3/4 drug-related AE include AST increased (15%), erythema (15%) and hypotension (15%). Preliminary efficacy data (RECIST v1.1) from 17 evaluable pts (2 pts had insufficient follow-up) showed no objective responses; 12 pts had a BOR of SD (63%) including 4 pts (24%) with a ≥10% reduction in target lesions. With median follow-up of 1.8 mo, the disease control rate (16 wks) was 32%. Conclusions: The intra-patient escalation regimen of IMCgp100 results in a 50% increase in dose above the FIH Phase 1, acceptable safety profile, and preliminary efficacy in UM pts. Considering the dismal prognosis of metastatic UM, the PFS observed in this study is encouraging. A Phase 2 expansion cohort and separate pivotal trial of IMCgp100 in advanced UM are ongoing. Clinical trial information: NCT02570308.

G-protein-coupled receptor heterodimerization: assay technologies to clinical significance

The concept of G-protein-coupled receptor (GPCR) oligomerization has existed for many years, but has only recently received scrutiny from the pharmaceutical industry. The new interest in this theory has arisen not only because technologies to exploit GPCR oligomers are now available, but also because GPCR oligomerization has the potential to explain previously anomalous pharmacology and to provide an array of new therapeutic targets. The emergence of higher order GPCR organization adds a layer of complexity in the context of cellular control, and indeed drug discovery. This review outlines the current knowledge surrounding the oligomerization of GPCRs and describes effective assays for exploiting oligomerization in drug discovery. The clinical significance of oligomerization and the most promising strategies for therapeutically targeting GPCR oligomers are discussed.

Combining child welfare and substance abuse services: a blended model of intervention

Montgomery County, Maryland's Child Welfare Services (CWS) and Adult Addiction Services (AAS) developed an initiative to address the requirements of the Adoption and Safe Families Act (ASFA) while meeting the needs of families and the community of providers. A blended model of intervention was determined to be the best strategy to achieve the dual mandates of CWS and alcohol and other drugs (AOD) providers. Drawing from criminal justice, systems theory, social work, and addiction treatment, the approach made use of graduated sanctions or levels of intensity in providing services, engaging client participation, and engendering motivation. This article proposes strategies at client and organizational levels to understand the process of adaptation to ASFA and to guide planning for blending services.

Medical complications after stroke: a multicenter study

BACKGROUND AND PURPOSE

This prospective, multicenter study was performed to determine the frequency of symptomatic complications up to 30 months after stroke using prespecified definitions of complications.

METHODS

We recruited 311 consecutive stroke patients admitted to hospital. Research nurses reviewed their progress on a weekly basis until hospital discharge and again at 6, 18, and 30 months after stroke.

RESULTS

Complications during hospital admission were recorded in 265 (85%) of stroke patients. Specific complications were as follows: neurological-recurrent stroke (9% of patients), epileptic seizure (3%); infections-urinary tract infection (24%), chest infection (22%), others (19%); mobility related-falls (25%), falls with serious injury (5%), pressure sores (21%); thromboembolism-deep venous thrombosis (2%), pulmonary embolism (1%); pain-shoulder pain (9%), other pain (34%); and psychological-depression (16%), anxiety (14%), emotionalism (12%), and confusion (56%). During follow-up, infections, falls, "blackouts, " pain, and symptoms of depression and anxiety remained common. Complications were observed across all 3 hospital sites, and their frequency was related to patient dependency and duration after stroke.

CONCLUSIONS

Our prospective cohort study has confirmed that poststroke complications, particularly infections and falls, are common. However, we have also identified complications relating to pain and cognitive or affective symptoms that are potentially preventable and may previously have been underestimated.

Recognition of facial expressions of emotion by persons with mental retardation. A matched comparison study

Children and adults with mental retardation were tested on their ability to recognize facial expressions of emotion. The sample consisted of 80 children and adults with mental retardation and a control group of 80 nonhandicapped children matched on mental age and gender. Ekman and Friesen's normed photographs of the six basic emotions (anger, disgust, fear, happiness, sadness, and surprise) were used in a recognition task of facial expressions. Subjects were individually read two-sentence stories identifying a specific emotion, presented with a randomized array of the six photographs of the basic facial expressions of emotion, and then asked to select the photograph that depicted the emotion identified in the story. This procedure was repeated with 24 different stories, with each of the six basic emotions being represented four times. Results showed that, as a group, individuals with mental retardation were not as proficient as their mental-age-matched nonhandicapped control subjects at recognizing facial expressions of emotion. Although adults with mild mental retardation were more proficient at this task than those with moderate mental retardation, this finding was not true for children. There was a modest difference between the children with moderate mental retardation and their nonhandicapped matched controls in their ability to recognize facial expression of disgust.

Enhancing the ability of adults with mental retardation to recognize facial expressions of emotion

The ability to recognize accurately and respond appropriately to facial expressions of emotion is essential for interpersonal interaction. Individuals with mental retardation typically are deficient in these skills. The ability of 7 adults, 1 with severe and 6 with moderate mental retardation, to recognize facial expressions of emotion correctly was assessed. Then, they were taught this skill using a combination of a discrimination training procedure for differentiating facial movements, directed rehearsal, and Ekman and Friesen's "flashing photograph" technique. Their average increase in accuracy over baseline was at least 30% during the course of the training and over 50% during the last 5 days of the training phase. Further, these individuals were able to generalize their skills from posed photographs to videotaped role plays and were able to maintain their enhanced skills during the 8 to 9 months following the termination of training. This is the first study to show that individuals with mental retardation can be taught skills that enhance their ability to recognize facial expressions of emotion.

Recognition of facial expressions of emotion by persons with mental retardation

A sample of 511 children and adults with mental retardation or borderline intelligence (1 SD below the mean IQ) and children of average intelligence were tested on their ability to recognize the six basic facial expressions of emotion as they are exemplified in Ekman and Friesen's (1975) normed photographs. Each subject was shown four sets of six photographs, one of each emotion. Subjects were read 24 short stories; after each one they were asked to point to the photograph that depicted the emotion described. Children and adults with mental retardation or borderline intelligence were less proficient at identifying facial expressions of emotion than were children of average intelligence. Among individuals with mental retardation or borderline intelligence, recognition of accuracy of facial emotion increased with IQ. Among individuals with average intelligence, recognition accuracy increased with age.